At least 70% of all patients with diabetes mellitus will develop polyneuropathy and its associated morbidities, including loss of sensation, pain, impaired mobility, ulcers and even amputation of affected extremities. The pathogenesis of diabetic polyneuropathy (DP) is very complex, with tissue ischemia, inflammation, protein kinase C activation, protein glycation all having been identified as important mechanisms, although other factors are also likely to play a role. One potentially overlooked factor which may have an important influence on the pathogenesis of DP is that of temperature. Even relatively mild cooling of the distal extremities could enhance tissue ischemia, augment immune complex deposition, lead to further activation of protein kinase C, and increase protein glycation. Given the impaired distal thermoregulation of individuals with DP, a cycle of worsening neuropathy may develop where further nerve and vascular dysfunction lead to further impairment in thermoregulation, causing a more rapid progression of the DP itself. Despite this potentially important connection, only some limited epidemiological has been obtained which suggests that patients living in colder climates have a higher incidence of DP than those living in warmer climates. The goal of this proposal is to examine the effect of temperature on the development of DP in rats in order to determine: 1. how intermittent cooling impacts nerve health; and 2. through what potential mechanisms such effects occur. We plan to achieve this via three specific aims. All three aims will involve the study of a group of healthy rats and a group of streptozotocin-injected diabetic rats. Subsets of rats from each of these groups will be exposed to either steady room temperature (~23[unreadable]C), intermittent cool temperature (~16[unreadable]C), or intermittent cold (~10[unreadable]C) for 16 weeks. In the first aim, we will assess and compare how nerve function changes over time in each group, as measured by behavioral and electrophysiological methods. In the second aim, we will assess the microscopic pathology of the microvasculature, nerve, and skin at the conclusion of the 16-week study period. In the third aim, we will determine how cold-exposure affects molecular markers in these animals, using ELISA and microarray techniques. If these experiments are able to demonstrate a relationship between cold-exposure and the development of DP, then future studies in animals and human subjects may help further elucidate the specific mechanisms by which this interaction occurs. But more importantly, such results would indicate that stabilization of distal limb temperature may help slow the progression of this debilitating disorder. [unreadable] [unreadable] [unreadable] [unreadable]